1999 Forest
Insect and Disease
Conditions for the Southern
Region

Note: bold hypertext
links within the narratives (e.g., Dogwood anthracnose)
will take visitors to the on-line publication, The Health of Southern
Forests that displays additional graphics and discusses the biology
and southern history of the causal agent in more detail. Not all causal
agents are linked. Non-bolded links provide for within-document
navigation.

Most
Significant Conditions in Brief

Once again, weather
dominated the forest stressor news in 1999. The year was a terrible one
for the State of North Carolina. Hurricanes Floyd and Dennis dumped a
massive amount of water throughout the whole of the eastern part of the
state. Ramifications of this flooding will be realized for years to come
as secondary insects and pathogens doubtless exploit the weakened trees.
Tornadoes caused significant blowdowns in West Tennessee and West-central
Arkansas. The drought of 1998 continued with a vengeance into 1999 across
much of the South. From Texas to Virginia, foresters reported new plantation
failures and other drought-related problems. Ironically, the western portion
of North Carolina was among the driest areas in the South -- this while
the eastern part of the State suffered under the aforementioned flooding.

Southern pine beetle
activity was moderate in the central part of the South. For Texas, this
was the second straight year of no activity – a most unusual occurrence.

Once again, there
was no gypsy moth defoliation in Virginia. This is the continuing effect
of an Entomophaga maimaiga insect pathogenic fungal outbreak that
caused gypsy moth populations to collapse throughout their eastern range.

Diseases such as fusiform
rust and annosus root disease continue to take a steady toll on forests
and trees throughout the South. Again, foresters, entomologists, and pathologists
continued to monitor and evaluate a number of introduced insect and disease
pests such as the hemlock woolly adelgid. These exotics pose special threats
to the resource because they typically have no, or few, natural enemies
here to hold them in check.

Insects:
Native

As in 1998, due to
the summer drought, black turpentine beetle activity was at a higher than
normal level throughout much of the South. This insect is most evident
in trees stressed by drought, logging injury, and similar disturbances.
Impacts were especially noteworthy in Texas and Tennessee.

Buck
moth, Hemileuca maia, on live oak and other hardwoods in Louisiana
[return]

Buck moth defoliation
has been a problem in New Orleans for a number of years. It continues
to be locally abundant in the city and of particular concern in the Federal
Historic Districts. Pheromone trapping of adult moths has been utilized
to identify hot spots for further evaluation.

In North Carolina,
the 1998 outbreak in the Charlotte area has subsided. No control other
than burlap banding was undertaken, and the pheromone trapping surveys
show populations to be so low that no treatments are planned for 2000.
Virginia sustained heavy fall cankerworm defoliation in Fairfax and Chesterfield
Counties. Meanwhile, Tennessee reported the lowest levels of cankerworm
ever recorded in the northeast quadrant of the state.

Forest
tent caterpillar, Malacosoma disstria on tupelo gum and other hardwoods
in Louisiana, North Carolina, and Texas. [return]

Defoliation occurred
on 79,000 acres of forested wetlands in Louisiana. In North Carolina,
93,000 acres along the Roanoke River were defoliated, with 30,400 acres
classified as “severe.” In Texas, local infestations of the forest tent
caterpillar occurred in the Dallas/Ft. Worth area.

Defoliation occurred
on 300,000 acres of forested wetlands in southeastern and south central
Louisiana. It is estimated that almost half of the defoliated acreage
(approximately 140,000 acres) is serious enough to cause significant growth
loss. Repeated annual defoliation has caused dieback and mortality on
sapling and pole-sized cypress in permanently flooded areas. The outbreak
now borders the City of New Orleans.

In Texas, tip moth
infestations increased from 50 percent of pine tips in 1998 to about 75
percent in 1999, but some areas completely escaped infestation for unknown
reasons. Mississippi reported sharp increases in tip moth infestations.
In Georgia, tip moth was most troublesome along the coastal plain where,
in combination with drought, the pest has been particularly damaging.
Florida recorded especially high levels of tip moth, probably due to the
compounding Impact of summer drought. South Carolina noted that damage
was most pronounced in old fields, with the August generation causing
the most damage. Nevertheless, in Tennessee, the spectacular outbreak
subsided, with 1999 classified as an average tip moth year.

Drought conditions
throughout the growing season across much of the South led to another
year of higher-than-normal levels of Ips pine engraver beetles. Small
groups of Ips-killed trees were scattered throughout the forest
stands, consequently losses are difficult to quantify. In the Gulf coastal
states, activity increased into late summer and early fall. Louisiana
surveys showed 120 multiple-tree infestations. Texas also reported unusually
heavy Ips activity for a second straight year. In the Carolinas,
the situation was much the same, with high levels of Ips losses
throughout both states. South Carolina foresters noted that Ips
were common on the edges of southern pine beetle spots. In Georgia, Ips
are estimated to have killed almost 690,000 trees over about 2,300 acres.
As with South Carolina, many pine engraver spots were associated with
southern pine beetle. In Tennessee, losses were on the increase statewide,
particularly in West Tennessee. Nevertheless, Florida Ips activity
declined in 1999, apparently due to continuing recovery from the 1998
wildfires.

Several species of
pine sawfly were active across the South in 1999. Infestations of the
blackheaded pine sawfly, Neodiprion excitans, were present in seven
East Texas counties. Some areas were completely defoliated. In Louisiana,
the loblolly sawfly, (Neodiprion taedae linearis) defoliated several
thousand acres of loblolly pine approaching maturity in the north central
part of the state, prompting private industry to treat 600 acres from
the air. This same species also defoliated scattered urban pine plantings
in northwest and middle Tennessee. In Florida, the redheaded pine sawfly,
N. lecontei, defoliated young stands of longleaf pine in Citrus,
Flagler, and Lake Counties. Virginia foresters recorded Hetrick’s sawfly
(N. hetricki) defoliating loblolly pine in the southeastern piedmont
and nearby coastal plain areas. In North Carolina, redheaded, Virginia
(N. pratti pratti) and introduced pine sawflies (Diprion similis)
stripped pines of their needles at various locations in the western part
of the state.

Weevil damage declined
significantly from 1998 in Texas. This is probably because most plantings
in 1999 were actually replantings of trees killed during the 1998 drought
(the delay for replanting ameliorated the risk of weevil damage). However,
Mississippi reported an increase in reproduction weevil damage. In Georgia,
pine reproduction weevils caused light to moderate damage staterwide,
with heaviest damage on tracts smaller than 10 acres. Many states now
pre-treat some seedlings with Pounce® insecticide as protection against
weevil attack.

During 1999, most
southern pine beetle (SPB) activity was concentrated in the central South,
with Alabama, Tennessee, South Carolina and North Carolina reporting significant
losses (chart). Meanwhile, Arkansas,
Louisiana, Oklahoma, and Texas reported no confirmed SPB spots on state
or private lands. For Texas, this was the second straight year of no SPB
activity – a most unusual occurrence.

Alabama had the highest
levels of SPB activity across the South (map).
Forty-one of 67 Alabama counties were in outbreak status. Losses were
also high on the Bankhead National Forest in the northwest section of
the state. In North Carolina, outbreaks in the coastal area have abated,
and now have shifted to the western mountain counties and the piedmont.
Similarly, Tennessee mountain and foothills counties showed some of the
heaviest losses in the Volunteer State, but southwestern Tennessee counties
also marked heavy SPB losses. South Carolina’s nine outbreak counties
were in the western and upstate counties in the western piedmont, foothills,
and mountains, but an extremely hot 1999 summer caused many spots to collapse.
In Virginia, the 1998 mountain counties epidemic collapsed, with widely
scattered spots in the piedmont and coastal areas showing an upward trend
at year-end. Florida reported a late summer build up of SPB in Hernando
County (just north of Tampa). This activity was unanticipated given the
relatively small and disjunctive acreage of loblolly pine occurring at
the southern end of the species’ range. It is also the farthest south
in the state that SPB has ever been reported. Most of the infestations
are occurring in residential areas and the wildland/urban interface around
the City of Brooksville.

The Texas leafcutting
ant, or town ant, does not eat vegetation per se, but removes the
foliage to its subterranean chambers where it uses a substrate on which
it cultivates a fungus food. In 1999, it continued to defoliate pine plantations
throughout east Texas and central Louisiana on sites with deep sandy soils.

Insects:
Nonnative

Fraser fir has a very
limited range in the Southern Appalachian Mountains and appears almost
exclusively in pure stands on the highest mountain peaks or in combination
with red spruce at somewhat lower elevations (map).
Since the first introduction of the balsam woolly adelgid, approximately
65,000 acres of Fraser fir have been affected. The insect attacks trees
of all age classes, but prefers the older fir trees. Adelgid populations
were again high in 1999.

In 1999, aerial surveys
in early July failed to detect any noticeable defoliation in Virginia.
This is the continuing after effect of an insect pathogenic Entomophaga
maimaiga fungus epizootic that caused gypsy moth populations to collapse
throughout the eastern range. However, ground surveys located apparently
healthy local populations in several mountain and piedmont counties. Consequently,
the potential for limited local area defoliation in Virginia is greater
for next year than it was for 1999.

In Tennessee, two
infestations in Overton and White counties were eradicated. Over 1900
acres in Scott County were sprayed with Bacillus thuringiensis
where 224 moths were captured in 1998 and 11 in 1999. Two ground treatments
are planned for Sevier and Cumberland Counties in 2000.

In Georgia, gypsy
moth infestations were eradicated in the City of Conyers. No new infestations
were discovered during 1999.

In North Carolina
and Georgia, 23,000 acres in and around the town of Highlands, NC were
treated as a part of a gypsy moth eradication program. Follow-up trapping
showed very few moths and no treatments are planned there in 2000.

In Arkansas, delimiting
and trapping continues in Carroll, Marion, and Newton Counties in the
aftermath of an eradication treatment carried out from 1993-95. Only three
moths were caught in Newton County in 1999, with none caught in Carroll
or Marion Counties. Trapping will continue within an expanded area in
Newton County, but no eradication treatments are planned for 2000.

The Gypsy Moth Slow-the-Spread
Project moved toward operational status in 1999. Trapping and treatments
were carried out in eight states from North Carolina to Wisconsin. Within
the boundaries of the Southern Region, 9,090 acres were treated in eastern
North Carolina and 24,640 acres in eastern and western Virginia. Additional
monitoring and treatment activities will be carried out in 2000.

Hemlock
woolly adelgid, Adelges tsugae, on hemlock in North Carolina and
Virginia [return]

This insect threatens
the entire range of eastern hemlock (map),
and is found throughout Virginia wherever hemlock is found in abundance,
as well as in five North Carolina counties. No new infested counties were
added to the list in 1999. The USDA Forest Service and North Carolina
State University cooperated in the evaluation of a release of predaceous
beetles in Hanging Rock State Park in Stokes County.

Pink
hibiscus mealybug, Maconellicoccus hirsutus, on hibiscus and many
other species in Puerto Rico and the U. S. Virgin Islands. [return]

The pink hibiscus
mealybug has now spread to over 25 Caribbean islands. It was detected
in Puerto Rico in 1997, but has not spread to Florida. The USDA Forest
Service and Animal and Plant Health Inspection Service, Plant Protection
and Quarantine staffs are working together to rear parasites to control
this pest. Mealybug population reductions of 85-90 percent have been
achieved at release sites.

Localized mortality
and growth loss occurred throughout the South in 1999 (map).
Alabama and Texas reported losses, with the Texas losses occurring mostly
in the northeast corner of the state. In South Carolina, annosus root
disease combined with drought to cause increased mortality in infected
stands.

Fusiform rust is the
most damaging disease of loblolly and slash pine in the South. Other pine
species can also be infected, but little damage or mortality occurs. An
estimated 13.8 million acres of loblolly and slash pine have at least
10 percent of trees infected. Georgia is the most heavily impacted state,
with 4.6 million acres (49 percent of host type) affected. Texas surveys
show that the disease has been on the decline for the past few years.
Because of the exceptionally dry weather throughout much of 1999, rust
incidence across the region was relatively low for the year (the fungus
depends on wet weather for spread and distribution).

Littleleaf
disease, Phytopthora cinnamomi, on loblolly and shortleaf pines
in Alabama, Georgia, North Carolina, South Carolina, Tennessee, and Virginia.
[return]

Littleleaf disease
continues to cause growth loss and mortality across the Piedmont areas
of the affected states. Shortleaf pine is highly susceptible, while loblolly
pine is affected, but at a later age. Many of the stands that were converted
from shortleaf to loblolly to reduce the impact of this disease are not
reaching their age of susceptibility. These stands are often attacked
by bark beetles once weakened by root infection.

Oak
wilt, Ceratocystis fagacearum on live and red oaks in North Carolina,
South Carolina and Texas. [return]

Oak wilt continues
to be a devastating killer in 60 counties in central Texas. Urban, suburban,
and rural oaks are affected. Live oaks are the premier tree species in
the region and are highly valued for beauty, shade, and wildlife benefits.
The Texas Forest Service is in the 12th year of a cooperative
suppression project. Since the project’s inception, more than 2.4 million
feet (> 450 miles) of barrier trenches have been installed around 1,600
oak wilt infection centers in 34 counties. In the last several years,
the Army Corps of Engineers has implemented suppression efforts on 4 central
Texas reservoirs. The U. S. Fish and Wildlife Service has initiated
suppression efforts at the Balcones Canyons National Wildlife Refuge near
Austin, Texas.

Beech bark disease
was not found in any additional counties in 1999 (map),
but the disease continues to intensify within the currently affected areas.
Beech bark disease was first reported in the Great Smoky Mountains National
Park in 1994. However, the first mortality in the South was reported as
early as the mid-1980’s in northern Virginia. This is well outside the
previous known distribution. Tree mortality continues to intensify in
Tennessee along the Appalachian Trail in Blount, Cocke, and Sevier Counties
within the Great Smoky Mountains National Park. The disease intensified
at a greater rate than predicted, and it is spreading down the slopes
toward the Cherokee national Forest.

Scattered to localized
mortality continues to occur at low severity levels in urban and wild
populations of elm. In Georgia, Dutch elm disease killed hundreds of elms
during the 1999 summer drought. Most reports came from larger cities including
Atlanta, Augusta, Macon, and Rome.

This disease has been
in the South at least 40 years (map),
and is believed to have killed 3 of every 4 butternuts in North Carolina
and Virginia. The fungus kills trees of all ages. Butternut canker is
expected to spread and kill most of the resource, including regeneration.
The species will be replaced by other species on these sites (e.g., black
walnut). It is too early to project the benefits of selection and breeding.
However, trees exhibiting resistance have been found in Arkansas, North
Carolina, Tennessee, Kentucky and Virginia.

Only scattered trees
across the region are infected, but impacts can be locally significant.
In Georgia, pitch canker is associated with pine plantations near chicken
houses. The ammonia released from the brood houses creates conditions
on the trees conducive to infection. The damage is usually confined to
the area within the plantation nearest exhaust fans. All species of pine
(slash, longleaf, and loblolly) are affected. Chicken houses are becoming
a common sight throughout the coastal plain of Georgia. Thus, problems
associated with pitch canker are expected to increase there, especially
during droughts. Similar problems have been reported in North Carolina
when chicken waste has been used as fertilizer in pine plantations.

Although a small area
of upland hardwoods in extreme southern Virginia continues to show decline,
research by the Southern Research Station showed in 1999 that claims of
widespread decline of northern hardwoods in the Southern Appalachians
are highly exaggerated. The report also dispelled the myth that air pollution
is a significant causal agent for the hardwood declines in the Appalachians.
A summary of the report, written by Dr. Jim Steinman of the USDA Forest
Service, is available in news format on the Internet at:

Oak
decline, (abiotic and biotic influences) on oaks and other hardwoods regionwide.
[return]

The severe summer
drought of 1998 continued into 1999, with both the Ozark and Appalachian
mountain areas taking the brunt of the moisture deficit. Oaks were particularly
hard hit, with North Carolina and Virginia incurring heavy losses on south-facing
slopes. Similarly, Tennessee noted increased losses of both red and white
oak, with white oaks especially hard hit in the Appalachians. Arkansas
reported widespread red oak mortality in the north-central part of the
state. In Georgia, oak mortality was heaviest on rocky ridges and side
slopes in the mountains. Drought is just one component of oak decline,
a syndrome resulting in dieback and mortality of dominant and co-dominant
mature oaks. Other causal factors are stressors include frost, defoliation
by insects (including the gypsy moth) and secondary pests such as Armillaria
root disease and two-lined chestnut borer (Agrillus bilineatus)
and hypoxylon canker. Oak decline and gypsy moth have been shown to interact:
severe defoliation by gypsy moth can induce oak decline in previously
unaffected areas, and in areas of pre-existing oak decline, gypsy moth
defoliation causes increased mortality. Host, age, and site conditions
also play a role.`

Seed
Orchard Insects and Diseases

Coneworms caused a
25 percent cone loss in untreated areas of state seed orchard in Texas
in 1999 compared to 5 percent in the treated area. Elsewhere in the South,
coneworm numbers were relatively static, except for Florida, where a prevalence
of cone rust is contributing to unusually high coneworm populations at
the Withlochoochee Seed Orchard.

Damping-off is the
most common disease problem facing southern nurseries. Loss of seedlings
to damping-off varies greatly from year to year owing to the interaction
of pathogenic fungi (species of Fusarium, Pythium, Rhizoctonia, and
Phytopthora) and environmental conditions. Seedling losses can be
severe when germination is slow due to cold, wet weather. Losses in 1999
were lower than normal due to the very dry weather which inhibits fungus
development. Nevertheless, North Carolina reported scattered damping off
in southern yellow pine and white pine seed orchards.

Other
Stressors

Wind in Arkansas,
North Carolina and Tennessee affecting southern yellow pines and hardwoods.

The year 1999 was
a terrible one from a natural destruction perspective in North Carolina.
Hurricanes Dennis and Floyd dropped a massive amount of water throughout
the whole of eastern North Carolina. Although blowdown damage was not
nearly as destructive as other recent Hurricanes (e.g., Hurricane Hugo),
the consequences of the devestativg flooding are yet to be fully realized.
For example, the North Carolina Division of Forest Resources lost a nursery/seed
orchard facility valued at 1.5 million dollars, and the ramifications
of not providing the citizenry with seedlings is yet to be calculated.
The Division estimates that 71 million ft3of timber
were lost to blowdown, with another 80 million ft3 lost
to flooding.Almost 15,000 acres of reforestation projects
were destroyed. Total direct loss of trees and timber exceeds $89 million.
The full impact of these Hurricanes will not be felt for years to come.
History shows that southern pine beetle populations often build up to
outbreak levels following flooding, and other insects and diseases are
also likely to flourish in the storm-stressed forests of the piedmont
and coastal plain.

In other incidents,
a tornado touched down in west Tennessee, damaging trees along a 20-mile
path. Another tornado damaged timber across a 600-acre swath in Handeman
County, Tennessee. A severe windstorm in Hot Springs, Arkansas during
the summer damaged 3,000 acres of timber. Approximately 500 board feet
per acre was damaged.

Fire damage in
Florida on various tree species.

The massive wildfires
throughout Florida in the summer of 1998 caused mortality, but also predisposed
trees to a variety of opportunistic pathogens and insects. While related
tree mortality declined dramatically in 1999, Florida resource managers
are still alert for secondary insects and diseases in fire-stressed stands.

Hail on various
species in Mississippi and South Carolina.

Three spring hailstorms
were particularly destructive to forests in Mississippi and South Carolina
in 1999. In Mississippi, the single hailstorm defoliated trees in portions
of Greene, Jones, Perry, and Wayne Counties in the southeastern area of
the state. Because most of the hardwoods had not leafed out, defoliation
was confined largely to conifers, although bark damage occurred to twigs
and branches of both pines and hardwoods. Field surveys showed that most
trees refoliated adequately, and there was little mortality. Some dieback
might be expected in the future due to branch canker organisms exploiting
the damaged bark.

In South Carolina,
two separate hail storms in late April and early May caused defoliation
in Aiken, Saluda, and Newberry counties in the western part of the state,
and Marlboro County in the east. As in Mississippi, both hardwoods and
conifers were impacted, but defoliation was worse among pines. The South
Carolina Forestry Commission estimates that 47,700 acres were affected
by a minimum of 50% defoliation. The Commission continues to monitor the
affected areas for opportunistic insects and disease exploiting weakened
trees.

Drought across
the region affecting many tree species.

Drought conditions
prevailed over much of the South in 1999. Arkansas, Florida, Georgia,
Kentucky, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina,
and Tennessee had severe to extreme drought conditions in portions of
each state. Texas has suffered drought for three of the past four years.
At the end of 1999, over 60 percent of the Southern Region was below normal
in precipitation with 20 percent showing a deficit from 3 to 6 inches
and 16 percent having a deficit of 6-9-inches. Drought contributed to
early defoliation, growth loss, and general tree stress. In many parts
of the South, a wet spring caused a rich flush of vegetative growth that
later could not be sustained because of the drought. Shallow rooted species
on rocky mountain sites were especially impacted in Virginia and North
Carolina. Hardwood mortality was particularly striking throughout Virginia,
and the secondary impacts to the stressed ecosystems will be felt for
years to come.

Many pine plantations
planted since the mid-1990's failed due to drought and have been replanted
more than once. It is estimated that 35% of the trees planted region wide
succumbed to drought in 1999 with losses in extreme drought areas reaching
60%. Overall, it is estimated that 25% of plantations planted in 1999
will require replanting.